South Carolina Pest Management Handbook for Field Crops - 2017

AQUATIC WEED CONTROL Cory Heaton, State Wildlife Specialist

Aquatic weeds in ponds or lakes can be controlled by physical removal, biological control, or . The method or combination of methods used will depend on factors such as target weeds, non‐target plants, and what the water is used for. Physical removal can be accomplished manually or with machinery. It is time consuming, expensive and normally used alone if other methods are not feasible. However, a certain amount of physical removal may be necessary in combination with the use of biological control and herbicides. Prior to initiating any control measures it is crucial to accurately identify species to be controlled. Herbicides and biological control agents are not equally effective on all species. Numerous websites and mobile apps can aid in species identification. You can also submit aquatic plant species to Clemson University’s Plant Problem Clinic through your local extension office for identification.

Biological control is an option for certain aquatic weeds. The major advantages are ease of application and no concern over damage to plants irrigated with treated water. Triploid grass carp can control many submerged vascular aquatic weeds. Grass carp are usually used to control all vegetation in a pond, rather than selectively controlling certain vegetation. Replacement stocking of grass carp is necessary when fish are lost. A permit is required to stock grass carp, and only triploid fish can be legally used in SC. Tilapia are stocked in the spring and control most algae species. The concern with tilapia is that they are tropical animals and usually die during cold winters thereby requiring an annual stocking. Tilapia are legal for use in SC. The South Carolina Department of Natural Resources (SC DNR) now requires a free of charge permit prior to stocking tilapia and triploid grass carp for aquatic weed control in SC. A permit can be obtained from SC DNR at 803‐734‐3891 or from registered dealers in SC. The short permit can be faxed (803‐734‐4748) for a rapid turn‐around. Check with your Department of Natural Resources to determine if grass carp and tilapia are legal to stock and if a permit is required in your state.

Diquat, , , flumioxazin, fluridone, , copper, sodium carbonate peroxyhydrate, 2,4‐D, carfentrazone, bispyribac, , penoxsulam, tompramezone, and imazamox compounds can be used safely in ponds used as irrigation sources if the manufacturer’s label directions are followed. Certain waiting periods may be required before using water for irrigation after the is applied, while in some cases waiting periods are not required. Various chemicals have different product formulations; only aquatic labeled and surfactants/adjuvants may be used in aquatic applications, by law.

Effective October 2011, aquatic applications in SC require a permit from South Carolina Department of Health and Environmental Control (SCDHEC). These permits are issued in accordance with the federal Clean Water Act and the National Pollution Discharge Elimination System (NPDES). Aquatic pesticide applicators may be required to submit a Notice of Intent (NOI), practice Integrated Pest Management (IPM), and develop a Pesticide Discharge Management Plan (PDMP) in addition to the basic permit requirements. The additional requirements are based on established application thresholds. The threshold for aquatic weed control applications is 200 acres’ treatment area or 20 miles of treated shoreline. Applicators below these levels are automatically covered by the SC general permit. Applicators above these levels will be required to submit a NOI, practice IPM, and possibly develop PDMP.

For more information on the NPDES permit please contact SCDHEC at (803) 898‐4157 or online at http://www.scdhec.gov/environment/water/npdes_pesticide.htm.

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Products for Use “To Waters Edge”

Aquatic applications in South Carolina do not always require products with full aquatic labels. In many instances, shoreline applications are made that do not involve product application directly into waters. Applications near but not into an aquatic environment can be made using products labeled for use “to waters edge”. Products to be utilized for such applications must be labeled accordingly. While many of the products labeled for this use have terrestrial labels, not all terrestrial labeled products are labeled for use along the water’s edge. It is the applicators responsibility select and only use products labeled specifically for this purpose.

Milestone Specialty Herbicide from Dow AgroSciences is an example of a product labeled for use to waters edge. The Milestone label states “It is permissible to treat non‐irrigation ditch banks, seasonally dry wetlands and transitional areas between upland and lowland sites only when dry. Milestone can be used to the waters edge. Do not apply directly to water and take precautions to minimize overspray to open water when targeting vegetation in and around non‐ flowing, quiescent or transient water….”. Label wording is not identical for every product. Always read the most current product label and only use products in accordance with the label.

Amount of Formulation for Application

Herbicide Rate* 0.3 to 2.6 gal/acre foot of 4.2 L or 13 to 108 lb of 10G/acre foot or 2.2 Aquathol to 22.0 lb of 63G/acre foot. Hydrothol 0.3 to 3.4 gal/acre foot of 2L or 11 to 136 lb of 11G/acre foot. Diquat 1 to 2 gal/surface acre of 2L. 2,4‐D 1 to 2 gal/surface acre of 3.8 L or 150 to 200 lb of 20G/surface acre. 0.6 to 3.4 gal of Chelated Copper/acre foot or 0.1 to 0.5 ppm elemental Copper Compounds copper. Fluridone 0.25 to 0.5 gal/surface acre. Check with company rep for exact rates. 0.75 to 1.5% solution, depending on the weed species, using hand held Glyphosate application equipment Triclopyr 2 to 8 quarts per surface acre of 3L. 4.0‐16.0 fl. oz. per acre for surface applications. 30‐50 ppb for water Tompramezone treatment Sodium Carbonate Peroxyhydrate 3 to 170 pounds per acre‐foot of 50G. Imazapyr 2 to 6 pints per acre. 3.4 to 13.5 fl. oz. per surface acre for floating vegetation ‐ 0.286 Carfentrazone gal/acre foot for submerged vegetation. Penoxsulam 10 to 150 ppb; Not to exceed 150 ppb per growing season. Follow label for specific rates. 32 to 64 fl. oz. per surface acre broadcast foliar application. 50 to 500 Imazamox ppb in water treatment 6‐12 oz. per surface acre for surface applications. 100‐400 ppb in Flumioxazin water treatment or subsurface applications 1‐2 oz. per acre for surface applications. 20‐45 ppb for water Bispyribac treatment or subsurface applications *Acre foot = 1 surface acre of water (43,560 ft2) 1 foot deep.

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Effectiveness of Herbicides for Aquatic Weed Control

Weed Copper complexes (Copper sulfate) 2,4‐D Diquat (Reward) Endothol Aquathol K & G Endothol Hydrothol G & 191 Fluridone Glyphosate Sodium Carbonate Peroxyhydrate Trichlopyr Imazapyr Carfentrazone Penoxsulam Imazamox Flumioxazin Bispyribac Tompramezone Algae Filamentous E P P ‐ G P P E ‐ ‐ ‐ ‐ ‐ E ‐ ‐ Planktonic E P G ‐ G P P E ‐ ‐ ‐ ‐ ‐ P ‐ ‐ Branched (Chara) E P G ‐ G P P P ‐ ‐ ‐ ‐ ‐ F P ‐ Nitella E P G ‐ G P P P ‐ ‐ ‐ ‐ ‐ F P ‐ Floating plants ‐ Bladderwort P P E ‐ ‐ E ‐ P ‐ ‐ ‐ ‐ G ‐ ‐ F Duckweeds P G1 G P P E P P ‐ E E E ‐ E ‐ ‐ Water hyacinth P E E ‐ ‐ P G P E E E E E P E G Watermeal P P P ‐ ‐ G P P ‐ ‐ G G ‐ E F ‐ Submersed plants Broadleaf watermilfoil P ‐ E E E E P P E ‐ G E ‐ G G F Coontail P G E E E E P P ‐ ‐ ‐ ‐ ‐ G P ‐ Egeria P P G F F E P P ‐ ‐ ‐ E ‐ ‐ ‐ ‐ Elodea P ‐ E F F E P P ‐ ‐ ‐ E ‐ E ‐ ‐ Eurasian millfoil P E E E E E P P E ‐ E E F G G ‐ Fanwort P F G E E E P P ‐ ‐ ‐ ‐ ‐ G ‐ ‐ Hydrilla F² P G G G E P P ‐ ‐ ‐ E F G E G Naiads P F E E E E P P ‐ ‐ ‐ G ‐ E ‐ F Parrotfeather P E E E E ‐ F P F E E G G G ‐ ‐ Pondweeds (Potamogeton) P P G E E E P P ‐ ‐ ‐ E G G G G E=excellent control (90 to 100%); G=good control (80 to 89%); F=fair control (70 to 79%); P=poor control (<70%). A blank space (‐) indicates weed response is not known. 1Ester formulations only. 2Copper complex only

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Effectiveness of Herbicides for Aquatic Weed Control – Continued

Weed Copper complexes (Copper sulfate) 2,4‐D Diquat (Reward) Endothol Aquathol K & G Endothol Hydrothol G & 191 Fluridone Glyphosate Sodium, Carbonate Peroxyhydrate Trichlopyr Imazapyr Carfentrazone Penoxsulam Imazamox Flumioxazin Bispyribac Tompramezone Emergent plants Alders P E F P P P E P ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ Alligatorweed P F P P P G E P E E G G G G E ‐ American lotus P E P P P F G P E E ‐ ‐ F ‐ ‐ F Arrowhead P E G G G ‐ E P ‐ E ‐ G ‐ G E G Buttonbush P E F P P P G P ‐ E ‐ ‐ ‐ G ‐ ‐ Cattails P G G P P F E P ‐ E ‐ ‐ E P ‐ ‐ Common reed P P P P P P G P ‐ E ‐ ‐ F‐G P ‐ ‐ Fragrant & white P E P P P E E P E E ‐ G F F ‐ waterlily Frogbit P E E ‐ ‐ ‐ ‐ P E E ‐ ‐ E G E ‐ Grasses, most P P P P P P G P ‐ E ‐ ‐ F ‐ ‐ ‐ Maidencane P P F ‐ ‐ F E P ‐ E ‐ ‐ ‐ ‐ ‐ ‐ Pickerelweed P G G ‐ ‐ P F P E E ‐ G E ‐ F ‐ Pond‐edge annuals P ‐ G ‐ ‐ E E P ‐ E ‐ ‐ ‐ ‐ ‐ ‐ Rush P P F P P F E P ‐ E ‐ ‐ ‐ ‐ ‐ ‐ Sedges and rushes P F F P P P G P ‐ E ‐ ‐ ‐ P F ‐ Slender spikerush P ‐ G ‐ ‐ G P P ‐ ‐ ‐ G F ‐ ‐ ‐ Smartweed P E F ‐ ‐ F E P E E ‐ G G P G F Spatterdock P E P P P E G‐E P E E ‐ ‐ G ‐ ‐ ‐ Southern watergrass P P ‐ ‐ ‐ G E P ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ Torpedograss P P P ‐ ‐ F G P ‐ E ‐ ‐ ‐ ‐ ‐ F Watershield P E P ‐ ‐ G G P ‐ ‐ ‐ ‐ G G ‐ ‐ Water pennywort P G G P P P G P E E ‐ E E G G ‐ Water primrose P E F ‐ ‐ F E P E E G ‐ F G ‐ ‐ Willows P E F P P P E P ‐ E ‐ ‐ ‐ ‐ P ‐ E=excellent control (90 to 100%); G=good control (80 to 89%); F=fair control (70 to 79%); P=poor control (<70%). A blank space (‐) indicates weed response is not known. 1Ester formulations only. 2Copper complex only

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Waiting Period (Days) Before Using Water After Application of Herbicides for Aquatic Weed Control

Common Name Trade Name Irrigation Fish Watering Swimming Consumption Livestock Copper Crystalline copper NR1 NR NR NR sulfate and various liquid organic copper complexes Water use restrictions vary by formulation and manufacturer. Certain Various labels allow irrigation if an approved chemical assay has reached 2,4‐D formulations and acceptable levels. A few labels allow irrigation with specific waiting 2 manufacturers periods. Certain labels may allow irrigation on established turf, immediately. CHECK INDIVIDUAL LABEL. Diquat Reward 1 to 33 NR 1 NR Weedtrine D 5 NR 5 NR Endothall Aquathol K 7 to 25 NR 7 to 25 NR Aquathol 7 to 25 NR 7 to 25 NR granular Aquathol 7 to 25 NR 7 to 25 NR Super K Hydrothol 191 7 to 25 NR 7 to 25 NR Hydrothol 191 7 to 25 NR 7 to 25 NR granular Avast, Sonar AS, 7‐30+ NR NR NR Sonar SRP, Fluridone Sonar PR, Sonar Q Rodeo, AquaNeat, NR NR NR NR Glyphosate AquaMaster, AquaPro Sodium Green Clean, Pak Carbonate 27, NR NR NR NR Peroxyhydrate Phycomycin Triclopyr Renovate 1204 NR5 NR Imazapyr Habitat 120 NR NR NR Carfentrazone Stingray 0‐146 NR 0 to 1 NR <30 ppb Turf Penoxsulam Galleon NR NR NR <1 ppb Others Imazamox Clearcast See note 7 NR NR NR Flumioxazin Clipper 5 days NR NR NR Bispyribac Tradewind < 1 ppb NR < 1 ppb NR Tompramezone Oasis < 1 ppb 0 0 0 1NR = No restrictions. 2Most formulations do not permit application to ponds used for irrigation or for watering dairy cattle. 3Three days for irrigation of turf and nonfood crops; five days for irrigation of food crops (including tobacco) or for preparation of agricultural sprays. 4No restriction for established grasses and assay to reduce restriction time. 514‐day restriction on grazing site and growing. Season grazing restriction on lactating livestock after irrigating pasture. 61 day if <20% of surface acreage is treated. 14 days if >than 20% is treated. Certified lab test of <5 ppb. 7 DO NOT use treated water for greenhouses, nurseries or hydroponics – bioassay for canola, onions, potatoes or sugar beets; other crops 1 day

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Common Aquatic Plants Consumed by Grass Carp1

Plants in order of common name preference hydrilla 1 hygrophila 9 maidencane2 (Panicum) 16 chara (muskgrass) 2 cattail² 10 parrot feather 16 pondweeds (Potamogetan) 3 torpedograss 10 know grass (Paspalum) 17 bushy pondweed (Southern naiad) 4 salvinia 10 water hyacinth 17 elodea 5 water‐aloe (Stratiotes) 11 giant bulrush² 18 watermeal 6 watercress 12 water lettuce 18 duckweeds 7 torpedograss 13 soft‐stem bulrush2 19 water‐fern (Azolla) 7 Eurasian watermilfoil 14 coontail 8 eel grass (Vallisneria) 15

1 Adapted from “Grass Carp ‐ A Fish for Biological Management of Hydrilla and Other Aquatic Weeds in Florida” by David L. Sutton and Vernon V. Vandiver, Jr., University of Florida IFAS, Bulletin 867; and from “Managing Aquatic Vegetation With Grass Carp ‐ A Guide For Water Resource Managers” edited by John R. Cassani, American Fisheries Society, Bethesda, Maryland.

2Young, succulent, underwater shoots are preferred. Some plants have the same number, which means grass carp like them equally

Aquatic Plant Management Internet References

AQUAPLANT – A Pond Manager Diagnostic Tool – Texas AgriLife Extension Service, Texas A&M University http://aquaplant.tamu.edu/

Aquatic Plant Control Research Program – U.S. Army Corps of Engineers http://el.erdc.usace.army.mil/aqua/

Aquatic Plant Information System http://el.erdc.usace.army.mil/aqua/apis/apishelp.htm

Center for Aquatic and Invasive Plants – University of Florida, IFAS http://plants.ifas.ufl.edu/

South Carolina Department of Health and Environmental Control – NPDES Permitting http://www.scdhec.gov/environment/water/npdes_pesticide.htm

South Carolina Department of Natural Resources – Commercial Aquatic Pesticide Applicators www.dnr.sc.gov/wildlife/publications/pdf/LakeMgtConsultants.pdf

Aquatic Plant Management Mobile Apps

AQUAPLANT – A Pond Manager Diagnostic Tool – Texas AgriLife Extension Service, Texas A&M University http://aquaplant.tamu.edu/useful‐apps/

AQUACIDE – Aquatic Herbicide Selection, Effectiveness, and Restriction Guide – Texas AgriLife Extension Service, Texas A&M University http://aquaplant.tamu.edu/useful‐apps/

PONDCALC – Pond Size and Volume Calculator – Texas AgriLife Extension Service, Texas A&M University http://aquaplant.tamu.edu/useful‐apps/

Aquatic Plants – Aquatic Plant Identification Tool –NC State University http://www.weedscience.ncsu.edu/aquaticweeds

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